Main objective aimed for primary grades, but has extensions for the intermediate grade levels.

Students will:**Conclude that oil and water are immiscible and can not be mixed.**Discover that an emulsifying agent can be added to two immiscible liquids to stabilize the two liquids to each other when mixed.**Conclude that the mixture of the three substances is called an emulsion.**Explain why an emulsion is not a solution.

**Number One:Have students see you measure out two - three cups of water and pour into the large jar. Add about 4 - 6 drops of food coloring to the water and mix (optional). Next measure out two - three cups of salad oil and pour into the jar.

Have the students observe what happens. Then pick a student volunteer to shake up the contents. Again, have the students observe what happens. Let the contents of the jar sit for 3 - 5 minutes.

Questions to ask:What is happening to the oil?Why do you think that is happening?Why is the oil in the top layer?

Explanation:It is impossible for oil and water to mix together. They are called immiscible- meaning that the two liquids can not be mixed together into a solution. When shaken, the oil droplets become suspended in the water. Eventually, the oil droplets enlarge to become a separate layer on top of the water. The oil is on the top layer because it is less dense than the water.

**Number Two:Tell students that they are now going to make some mayonnaise, but they must now get some oil and water to mix. Have them predict what would be needed to help the oil and water mix together. (Optional: create a prediction chart.) Next, have each student count off to create groups of four.

Experiment #1Procedure for students:1. Pour the vinegar into your jar.2. Pour the salad oil into the jar and put on the lid.3. Shake the contents very hard for 3 - 4 minutes, then let it sit 3 - 4 minutes. 4. Compare your jar with your teacher's jar.

Questions for data sheet:1. What happened in your jar?2. Which liquid remained on top?3. How does this compare to your teacher's jar?4. What does this mean for the vinegar?

Explanation:When shaken, the oil and vinegar seemed to mix. But when the contents were allowed to sit, the two liquids formed two separate layers. The oil remained in the top layer. As a result, this means that the vinegar must be made mostly of water.

Experiment #2Procedure for students:1. Put the egg yolks into the small cup or bowl.2. Beat the yolks until they are liquid.3. Pour the beaten yolks into the jar with the oil and vinegar and close the lid.4. Shake the contents very hard for 3 - 4 minutes.5. Observe what happens.

Questions for data sheet:1. Describe what happened in the jar now.2. Why do you think this happened?3. Put the hand lens to the jar. What do you see?

Explanation:The oil and the vinegar (water) mixed together much better when the egg yolk was added. The lecithin, which is a protein in the egg yolk, acts as an emulsifyingagent. Emulsifying agents have regions that associate with the oil and regions that associate with the vinegar (water). Thus the emulsifier (the egg yolk), acts as a bridge between both the oil and the water.

The lecithin molecules in the egg yolk formed a layer around the oil droplets and prevented the tiny droplets from coming together to make a separate layer. The egg yolk then enabled the oil to mix with the vinegar. The mayonnaise that is being created is an emulsion of oil droplets in water. This means that it is not a solution. A solution is made when two or more liquids are totally mixed together. Because the oil is still separate from the vinegar even with the egg yolk present, it can not be a solution.

The emulsion created here is a dispersion of one liquid (the oil), inside another liquid (the water), with an emulsifier (the egg yolk) acting as a bridge to the two liquids for stabilization.

Experiment #3Procedure for students:1. Add the mustard and the salt to the mixture.2. Again, shake very hard 3 - 4 minutes.

Questions for data sheet:1. Did anything happen to the mixture now?2. Taste. Describe the taste.3. How does this mayonnaise differ from the one bought from the store?

Performance Assessment:

Teacher will observe students watching the teacher demonstration with the oil and water, shaking and rolling the jar so that the students can conclude that oil and water are immiscible. As the students follow the procedures for each mini-experiment, they are to compare their jars to the demonstration jar, and complete the data sheets with their observations to determine that another substance (an emulsifying agent) added to the immiscible liquids will allow them to be somewhat mixed. The final assessment for this lesson is for the students to explain why the emulsion created is not a solution.

Conclusions:

Students are to be able to conclude from the experiment that emulsions and solutions are different.